Tap a hole in plastic barrel?

[Egon]

OK, more good information.

The barrel tipper is out. The upside down barrel is out.

Make a form to hold barrels lying on their side with a slight tip to it and the bungs vertically aligned and on the downward side with the small bung on the bottom. Plumb in the lower barrel bungs on a common line that goes to your pump. You can also use this line to fill barrels. On the top bungs put in a reducer and run a small line up from each bung to vent barrels.

 

[Robert_in_NY]

I was wrong, it was an 1.5" ball valve reduced down to 1.25".